Lighting Question about switch flippin

[KC75]

Through my first indoor auto tent grow i have learned a lot.
But...
Hopefully this isn’t dumb, but i have been running both veg and bloom switched on since first signs of pre flower.
Is there any time where you would want to go bloom switch only or keep running both switched on for light output.

 

[Arthur]

I believe the theory is in veg, bloom light is not neccessary...
In flower, I'd want everything possible on.